Operators and Expressions in Java Script

An operator is used to transform one or more values into a single resultant value. The values to which the operator is applied is referred to as operands. A combination of an operator and its operands is referred to as an expression . This is the value that results when an operator is applied to its operands.
1. Arithmetic Operators
Arithmetic operators are the familiar operators because they are used every day to solve common math calculations. The arithmetic operators that JavaScript supports are:

Subtraction or Unary negation
Returns the value then Increment
Return the value then Decrement

2. Logical Operators:
Logical operators are used to perform Boolean operators on Boolean operands and, or, not. The logical operators supported by Java Script are:
Logical Or
Logical and
Logical not

3. The comparison operators
Comparison operators are used to compare two values, supported by JavaScript are:
Strictly Equal
Not Equal
Strictly Not Equal
Less than
Less than or equal to
Greater than
Greater than or equal to

4. String Operators
String operators are those operators that are used to perform operations on strings JavaScript supports only the string concatenation (+) operator.
This operator is used to join two string. Eg. "xy" + "cd" produce "xycd".

5. Assignment Operator
Assignment operator is used to update the value of a variable. Few assignment operators are combined with other operators to perform a computation on the value contained in a variable and then update the variable with the new value.

6. Conditional Expression Ternary Operator 
JavaScript supports conditional expression operator. They are ? and : the conditional expression operator is a ternary operator since it take three operands, a condition to be evaluated and two alternative values to be returned based on the truth or falsity of the condition.

condition ? value 1: value ?

The condition expressed must return a value true or false. If the condition is true, value 1 is the result of the expression, otherwise value 2 is the result of the expression.

7. Special Operators
Java Script supports a number of special operators that do not fit into operator categories covered above.
1. delete Operators:
The delete operator is used to delete a property of an element or an object at an array index.

delete test[6]

Deletes the seventh element of test.
2. new operator:
new operator is used to create an instance of an object type.

test = new Array()

This will create a new JavaScript object of the type array and assign this array to a context area in memory called test.
3. void operator:
void operator does not return a value. It is typically used in Java Script to return a URL with no value.


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